Ink Setting on Coated Media-Importance of Pore Structure and Latex Content
Paper coatings are porous layers made up of mineral pigments,latex binder and a complex pore system.When coated paper and board are printed in sheet-fed offset,the ink oil becomes absorbed by the coating while the binder and pigment stay on top of the surface of the coating.The initial part of the oil absorption is recognized as ink setting.This process depends on both coating and ink properties,and the papermaker strives to engineer the coating for optimal ink setting properties.Too fast an ink setting may be detrimental for print gloss,in particular on gloss-coated substrates,while too slow an ink setting may give problems like piling,blocking and smearing.Unevenness in print,print mottle for instance is often due to an uneven ink setting.The mechanism of ink setting is not fully understood although the general understanding has drastically improved during the last two decades.The oil is basically absorbed by the pore system in a process called capillary absorption.However,there is also absorption by the latex binder by means of molecular diffusion,which results in latex swelling.The aim of the present paper was to learn about the relative importance of the capillary absorption and latex swelling.This was accomplished in a laboratory study where the binder amount in the coating was increased from 8 parts to 100 parts per 100 parts pigment,and by measuring the pore structure and ink setting using various techniques.It was concluded that capillary absorption was the main mechanism during the initial setting,while both capillary absorption and latex swelling controlled the time it took for the print to become touch-dry.
Ink,coated paper ink drying ink setting porosity latex binder
GORAN STROM MICHAEL KARATHANASIS
STFI-Packforsk AB,Box 5604,114 86 Stockholm,Sweden
国际会议
第二届国际造纸与环境学术会议(The Second International Papermaking & Environment Conference)
天津
英文
894-900
2008-05-14（万方平台首次上网日期，不代表论文的发表时间）